Lax policing in Rotherham lead to over 1,400 minors being sexually abusedGetty Images

A series of police failings left gangs free to sexually abuse more than 1,400 children in Rotherham over a 16-year period, says a report that calls upon the force to make a number of improvements to its investigation of sexual exploitation cases.

In the report from the National Crime Agency, dubbed Britain's FBI, South Yorkshire Police is told to make 48 improvements to its handling of sexual exploitation investigations.

Among failings that left the gangs free to groom and abuse vulnerable children, the report says that the force missed ways to protect victims, failed to coordinate operations with local authorities to tackle offenders, and missed ways to gather evidence on offences.

The NCA was brought in last year by chief constable David Crompton to oversee and review all current investigations into child sexual exploitation being carried out by South Yorkshire Police in Rotherham.

This followed an August report by Professor Alexis Jay, who said that children as young as 11 had been raped and abducted by multiple perpetrators between 1997 and 2013.

In a statement today (23 April), the NCA said: "Over the years, intelligence and investigative opportunities in relation to child sexual exploitation have been overlooked by South Yorkshire Police."

The report claims that South Yorkshire Police had begun to address past failings, but further opportunities may exist to pursue offenders identified in past investigations.

It backed claims from the Louise Casey, who in a government report said that the force did not work effectively with local authorities or use alternative means of gathering evidence.

Three operations are currently investigating criminal allegations of non-familial child sexual exploitation in Rotherham.

Though it judged that operations Clover and Monroe were making good progress, it found Operation Mark was not as well-developed, and would be taken forward under direct leadership from NCA Senior Investigating Officer Steve Baldwin.